1,721,021 research outputs found
Dynamics of Functionally Graded Beams on Viscoelastic Foundation
No full textIn the present contribution, the nonlinear dynamics of beams under axial time-dependent
excitation is studied. The beams, which rest on a linear viscoelastic foundation, are assumed as
axially graded both in terms of geometrical and material properties. The transversal motion
equation is derived under two main hypotheses, namely the beams satisfy the requirements of
Euler–Bernoulli theory and undergo moderately large de°ections (MLDs)
Nonlinear dynamics of a slender axially graded beam embedded in a viscoelastic medium
No full textIn the present contribution the nonlinear dynamics of beams under axial time-dependent excitation is studied. The beams, which are embedded in a linear viscoelastic medium, are assumed as axially graded in terms of material properties. The transversal motion equation is derived under two main hypotheses, namely the beams satisfy the requirements of Euler-Bernoulli theory and undergo moderately large deflections.</jats:p
Numerical applications of free discontinuity problems to folding and fracture
No full textThe aim of the thesis is the application of new numerical methods based on the theory of free discontinuities of E. De Giorgi to challenging fields of relevant practical interest in engineering, such as folding of thin walled tubes and propagation of fracture in brittle solids. Both the mathematical models to describe folding and fracture are based on the minimization of two competing energy forms: a volume and a surface energy. The variational formulation leads to the minimization (under displacement boundary conditions) of a functional F(K;u), where K is the set of discontinuous points of u. In order to perform the numerical search for the minimum of F, a powerful open code (developed by K. Brakke) named Surface Evolver has been adapted according to the purposes of the research at hand. Since the energy is non-convex the solution obtained through the algorithm is strongly dependent on the initial point. Starting from an initial faceted surface, the numerical code evolves the surface towards minimum energy through the nonlinear conjiugate gradient method
Dynamics of an axially graded beam on elastic foundation
No full textIn the present work, the nonlinear dynamics of an axially functionally graded beam on a viscoelastic linear foundation is studied. The beam, modeled using Euler–Bernoulli beam theory, is axially loaded by a harmonic excitation. The motion equation are derived under two other main hypotheses, namely the beam is inextensional and it undergoes moderate large deflections
Dynamics of an axially functionally graded beam under axial load
No full textThis paper considers the dynamics of a simply supported
beam under axial time–dependent load. The beam is made of an axially
functionally graded material. The motion equations are deduced
from the equilibrium in deformed configuration and no restriction is
made on the amplitude of the transversal displacement, but that naturally
imposed by the inextensibility assumption that is adopted in the
present study. The transversal motion equation, that is a partial differential
equation, is approximated by its Taylor expansion until third
order and then discretized through the Galerkin procedure
A damping device based on bistable springs
No full textA device for earthquake energy dissipation in shear–
type structures is introduced. The idea is basically to employ
chains made of bistable springs, that exhibit hysteretic behavior
Comparing numerical solutions for the propagation of brittle fractures based on local energy minimization with classical fracture mechanics results
No full textThe paper is focused on the comparison of some numerical results with the predictions in terms of energy levels, stress intensity factor and crack orientation, of Linear Elastic Fracture Mechanics and the criterion of maximum Energy Release Rate
for several Mode I, Mode II load combinations. In order to approximate solutions, the total potential energy is locally minimized via a descent method
Digital Twin Model of an Early Medieval Church: Entanglement of Historical Studies and Mathematical Methods
No full textInterest in digital twins has grown rapidly in recent years, both in science and industry. Moreover, due to their inherent ability to preserve fragile information, i.e., exposed to
the risk of loss, digital twins have become relatively common in archeology. However, far from
being just digital copies that allow one to learn about, share, preserve or even just enjoy an
artifact without the need to be at the location of the original physical entity, a digital twin is a
dataset that can evolve as new information becomes available or as the reference object changes.
With this idea in mind, the present work focuses on a multidisciplinary research activity devoted
to modeling the early medieval church of Santa Sofia in Benevento, Italy, which has undergone
alterations in its geometric and structural layout several times throughout its long history. To
track these modifications, a model was constructed combining data from a laser scanner survey of
the church in its current state and research sources documenting past configurations. The model
includes five main archeological and architectural phases backwards in time. The virtualization
process made use of both open source and proprietary software. In addition, to upload the
complex vault system of the church into the model, a specific computer code was developed to
reconstruct the surfaces from the point cloud making use of Coons patches based on Hermitian
cubics
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